syzbot


possible deadlock in ext4_ioctl

Status: auto-obsoleted due to no activity on 2024/01/09 18:17
Reported-by: syzbot+b430ca05e157e7bc3202@syzkaller.appspotmail.com
First crash: 519d, last: 420d
Similar bugs (5)
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream possible deadlock in ext4_ioctl ext4 44 579d 773d 0/28 auto-obsoleted due to no activity on 2023/08/20 05:40
linux-5.15 possible deadlock in ext4_ioctl (2) origin:lts-only C done 12 62d 133d 0/3 upstream: reported C repro on 2024/07/11 06:29
linux-6.1 possible deadlock in ext4_ioctl (2) 1 286d 286d 0/3 auto-obsoleted due to no activity on 2024/05/18 23:21
linux-6.1 possible deadlock in ext4_ioctl (3) 2 127d 159d 0/3 auto-obsoleted due to no activity on 2024/10/25 05:49
linux-5.15 possible deadlock in ext4_ioctl 1 292d 292d 0/3 auto-obsoleted due to no activity on 2024/05/12 20:19

Sample crash report:
======================================================
WARNING: possible circular locking dependency detected
6.1.55-syzkaller #0 Not tainted
------------------------------------------------------
syz-executor.4/20670 is trying to acquire lock:
ffff88809f84beb8 (&ei->i_data_sem/1){+.+.}-{3:3}, at: swap_inode_boot_loader fs/ext4/ioctl.c:426 [inline]
ffff88809f84beb8 (&ei->i_data_sem/1){+.+.}-{3:3}, at: __ext4_ioctl fs/ext4/ioctl.c:1424 [inline]
ffff88809f84beb8 (&ei->i_data_sem/1){+.+.}-{3:3}, at: ext4_ioctl+0x460f/0x5f60 fs/ext4/ioctl.c:1614

but task is already holding lock:
ffff88809000a0a0 (&ei->i_data_sem/2){++++}-{3:3}, at: ext4_double_down_write_data_sem+0x28/0x40

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #3 (&ei->i_data_sem/2){++++}-{3:3}:
       lock_acquire+0x1f8/0x5a0 kernel/locking/lockdep.c:5661
       down_read+0xad/0xa30 kernel/locking/rwsem.c:1520
       ext4_map_blocks+0x37a/0x1ca0 fs/ext4/inode.c:574
       ext4_getblk+0x1eb/0x7c0 fs/ext4/inode.c:854
       ext4_bread+0x2a/0x170 fs/ext4/inode.c:910
       ext4_quota_read+0x1a1/0x2c0 fs/ext4/super.c:7089
       read_blk fs/quota/quota_tree.c:55 [inline]
       find_tree_dqentry+0x190/0xc10 fs/quota/quota_tree.c:624
       find_tree_dqentry+0x48a/0xc10 fs/quota/quota_tree.c:640
       find_dqentry fs/quota/quota_tree.c:652 [inline]
       qtree_read_dquot+0x13f/0x650 fs/quota/quota_tree.c:672
       v2_read_dquot+0xbe/0x100 fs/quota/quota_v2.c:333
       dquot_acquire+0x188/0x680 fs/quota/dquot.c:459
       ext4_acquire_dquot+0x2e6/0x400 fs/ext4/super.c:6769
       dqget+0x752/0xe30 fs/quota/dquot.c:972
       __dquot_initialize+0x2d9/0xe10 fs/quota/dquot.c:1550
       ext4_process_orphan+0x57/0x2d0 fs/ext4/orphan.c:329
       ext4_orphan_cleanup+0xb70/0x1400 fs/ext4/orphan.c:474
       __ext4_fill_super fs/ext4/super.c:5533 [inline]
       ext4_fill_super+0x83ff/0x8b50 fs/ext4/super.c:5664
       get_tree_bdev+0x3fe/0x620 fs/super.c:1355
       vfs_get_tree+0x88/0x270 fs/super.c:1562
       do_new_mount+0x28b/0xae0 fs/namespace.c:3040
       do_mount fs/namespace.c:3383 [inline]
       __do_sys_mount fs/namespace.c:3591 [inline]
       __se_sys_mount+0x2d5/0x3c0 fs/namespace.c:3568
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x63/0xcd

-> #2 (&s->s_dquot.dqio_sem){++++}-{3:3}:
       lock_acquire+0x1f8/0x5a0 kernel/locking/lockdep.c:5661
       down_read+0xad/0xa30 kernel/locking/rwsem.c:1520
       v2_read_dquot+0x4a/0x100 fs/quota/quota_v2.c:332
       dquot_acquire+0x188/0x680 fs/quota/dquot.c:459
       ext4_acquire_dquot+0x2e6/0x400 fs/ext4/super.c:6769
       dqget+0x752/0xe30 fs/quota/dquot.c:972
       __dquot_initialize+0x2d9/0xe10 fs/quota/dquot.c:1550
       ext4_process_orphan+0x57/0x2d0 fs/ext4/orphan.c:329
       ext4_orphan_cleanup+0xb70/0x1400 fs/ext4/orphan.c:474
       __ext4_fill_super fs/ext4/super.c:5533 [inline]
       ext4_fill_super+0x83ff/0x8b50 fs/ext4/super.c:5664
       get_tree_bdev+0x3fe/0x620 fs/super.c:1355
       vfs_get_tree+0x88/0x270 fs/super.c:1562
       do_new_mount+0x28b/0xae0 fs/namespace.c:3040
       do_mount fs/namespace.c:3383 [inline]
       __do_sys_mount fs/namespace.c:3591 [inline]
       __se_sys_mount+0x2d5/0x3c0 fs/namespace.c:3568
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x63/0xcd

-> #1 (&dquot->dq_lock){+.+.}-{3:3}:
       lock_acquire+0x1f8/0x5a0 kernel/locking/lockdep.c:5661
       __mutex_lock_common kernel/locking/mutex.c:603 [inline]
       __mutex_lock+0x132/0xd80 kernel/locking/mutex.c:747
       dquot_commit+0x57/0x510 fs/quota/dquot.c:503
       ext4_write_dquot+0x1e8/0x2b0 fs/ext4/super.c:6753
       mark_dquot_dirty fs/quota/dquot.c:370 [inline]
       mark_all_dquot_dirty fs/quota/dquot.c:408 [inline]
       __dquot_alloc_space+0x574/0xf80 fs/quota/dquot.c:1780
       dquot_alloc_space_nodirty include/linux/quotaops.h:300 [inline]
       dquot_alloc_space include/linux/quotaops.h:313 [inline]
       dquot_alloc_block include/linux/quotaops.h:337 [inline]
       ext4_mb_new_blocks+0x1160/0x4820 fs/ext4/mballoc.c:5634
       ext4_new_meta_blocks+0x206/0x4f0 fs/ext4/balloc.c:739
       ext4_ext_grow_indepth fs/ext4/extents.c:1329 [inline]
       ext4_ext_create_new_leaf fs/ext4/extents.c:1435 [inline]
       ext4_ext_insert_extent+0xf43/0x4e50 fs/ext4/extents.c:2102
       ext4_split_extent_at+0x80e/0x10f0 fs/ext4/extents.c:3254
       ext4_force_split_extent_at fs/ext4/extents.c:338 [inline]
       ext4_swap_extents+0x12fb/0x2280 fs/ext4/extents.c:5717
       move_extent_per_page+0x1b5d/0x37c0 fs/ext4/move_extent.c:362
       ext4_move_extents+0x94f/0xe40 fs/ext4/move_extent.c:672
       __ext4_ioctl fs/ext4/ioctl.c:1358 [inline]
       ext4_ioctl+0x3a8d/0x5f60 fs/ext4/ioctl.c:1614
       vfs_ioctl fs/ioctl.c:51 [inline]
       __do_sys_ioctl fs/ioctl.c:870 [inline]
       __se_sys_ioctl+0xf1/0x160 fs/ioctl.c:856
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x63/0xcd

-> #0 (&ei->i_data_sem/1){+.+.}-{3:3}:
       check_prev_add kernel/locking/lockdep.c:3090 [inline]
       check_prevs_add kernel/locking/lockdep.c:3209 [inline]
       validate_chain+0x1667/0x58e0 kernel/locking/lockdep.c:3824
       __lock_acquire+0x125b/0x1f80 kernel/locking/lockdep.c:5048
       lock_acquire+0x1f8/0x5a0 kernel/locking/lockdep.c:5661
       down_write_nested+0x39/0x60 kernel/locking/rwsem.c:1689
       swap_inode_boot_loader fs/ext4/ioctl.c:426 [inline]
       __ext4_ioctl fs/ext4/ioctl.c:1424 [inline]
       ext4_ioctl+0x460f/0x5f60 fs/ext4/ioctl.c:1614
       vfs_ioctl fs/ioctl.c:51 [inline]
       __do_sys_ioctl fs/ioctl.c:870 [inline]
       __se_sys_ioctl+0xf1/0x160 fs/ioctl.c:856
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x63/0xcd

other info that might help us debug this:

Chain exists of:
  &ei->i_data_sem/1 --> &s->s_dquot.dqio_sem --> &ei->i_data_sem/2

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&ei->i_data_sem/2);
                               lock(&s->s_dquot.dqio_sem);
                               lock(&ei->i_data_sem/2);
  lock(&ei->i_data_sem/1);

 *** DEADLOCK ***

6 locks held by syz-executor.4/20670:
 #0: ffff88802a268460 (sb_writers#4){.+.+}-{0:0}, at: mnt_want_write_file+0x5a/0x1f0 fs/namespace.c:437
 #1: ffff88809000a218 (&sb->s_type->i_mutex_key#8){++++}-{3:3}, at: inode_lock include/linux/fs.h:756 [inline]
 #1: ffff88809000a218 (&sb->s_type->i_mutex_key#8){++++}-{3:3}, at: lock_two_nondirectories+0xde/0x130 fs/inode.c:1163
 #2: ffff88809f84c030 (&sb->s_type->i_mutex_key#8/4){+.+.}-{3:3}, at: swap_inode_boot_loader fs/ext4/ioctl.c:385 [inline]
 #2: ffff88809f84c030 (&sb->s_type->i_mutex_key#8/4){+.+.}-{3:3}, at: __ext4_ioctl fs/ext4/ioctl.c:1424 [inline]
 #2: ffff88809f84c030 (&sb->s_type->i_mutex_key#8/4){+.+.}-{3:3}, at: ext4_ioctl+0x25ff/0x5f60 fs/ext4/ioctl.c:1614
 #3: ffff88809000a3b8 (mapping.invalidate_lock){++++}-{3:3}, at: filemap_invalidate_lock include/linux/fs.h:801 [inline]
 #3: ffff88809000a3b8 (mapping.invalidate_lock){++++}-{3:3}, at: swap_inode_boot_loader fs/ext4/ioctl.c:402 [inline]
 #3: ffff88809000a3b8 (mapping.invalidate_lock){++++}-{3:3}, at: __ext4_ioctl fs/ext4/ioctl.c:1424 [inline]
 #3: ffff88809000a3b8 (mapping.invalidate_lock){++++}-{3:3}, at: ext4_ioctl+0x42d7/0x5f60 fs/ext4/ioctl.c:1614
 #4: ffff88802a26c990 (jbd2_handle){++++}-{0:0}, at: start_this_handle+0x1f51/0x21b0 fs/jbd2/transaction.c:463
 #5: ffff88809000a0a0 (&ei->i_data_sem/2){++++}-{3:3}, at: ext4_double_down_write_data_sem+0x28/0x40

stack backtrace:
CPU: 0 PID: 20670 Comm: syz-executor.4 Not tainted 6.1.55-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/06/2023
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x1e3/0x2cb lib/dump_stack.c:106
 check_noncircular+0x2fa/0x3b0 kernel/locking/lockdep.c:2170
 check_prev_add kernel/locking/lockdep.c:3090 [inline]
 check_prevs_add kernel/locking/lockdep.c:3209 [inline]
 validate_chain+0x1667/0x58e0 kernel/locking/lockdep.c:3824
 __lock_acquire+0x125b/0x1f80 kernel/locking/lockdep.c:5048
 lock_acquire+0x1f8/0x5a0 kernel/locking/lockdep.c:5661
 down_write_nested+0x39/0x60 kernel/locking/rwsem.c:1689
 swap_inode_boot_loader fs/ext4/ioctl.c:426 [inline]
 __ext4_ioctl fs/ext4/ioctl.c:1424 [inline]
 ext4_ioctl+0x460f/0x5f60 fs/ext4/ioctl.c:1614
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:870 [inline]
 __se_sys_ioctl+0xf1/0x160 fs/ioctl.c:856
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7fcfce67cae9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 e1 20 00 00 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fcfcf3c50c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007fcfce79c120 RCX: 00007fcfce67cae9
RDX: 0000000000000000 RSI: 0000000000006611 RDI: 0000000000000005
RBP: 00007fcfce6c847a R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 000000000000006e R14: 00007fcfce79c120 R15: 00007ffdf1c96c58
 </TASK>
netlink: 'syz-executor.4': attribute type 4 has an invalid length.

Crashes (2):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2023/09/28 13:02 linux-6.1.y d23900f974e0 c2ab1e5d .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan possible deadlock in ext4_ioctl
2023/06/21 04:29 linux-6.1.y ca87e77a2ef8 79782afc .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan possible deadlock in ext4_ioctl
* Struck through repros no longer work on HEAD.